1. Field of the Invention
This invention relates to a data recording device for carrying out recording of data onto an optical disc, a data reproducing device for carrying out reproduction of data recorded on an optical disc, and an optical disc in which a high recording density is realized.
2. Description of the Related Art
A CD (compact disc) system has been popularly used, which uses an optical disc with an outer diameter of about 120 mm and a thickness of about 1.2 mm as a recording medium and carries out reading or writing of signals by casting a light condensed by an objective lens onto the signal recording surface of the optical disc.
At first, the CD system was developed as a recording/reproducing system for digital audio data. As it has been popularly used, variations have been made to meet various purposes.
Particularly recently, since personal computers are broadly used as information processing means even in general households, a reproduction-only optical disc called CD-ROM (read only memory) has been popularly used as a recording medium for recording data handled by computers.
Also, as optical discs which enable recording of data while maintaining the reproduction compatibility with such a CD-ROM, a write-once optical disc like a CD-R (recordable) and a rewritable optical disc like a CD-RW (rewritable) have been developed and practically used.
Meanwhile, since the quantity of data handled by personal computers tends to increase more and more, it is strongly demanded to realize increase in the storage capacity of CD-ROM, CD-R, CD-RW and the like as recording media for recording such data.
To meet the above-mentioned demand, so-called double-density CD-R and CD-RW are being developed which have a recording density approximately twice that of the existing format while conforming to the CD format.
In the double-density CD-R and CD-RW, the recording density is increased to approximately twice that of the CD-R and CD-RW of the existing format (hereinafter referred to as normal-density CD-R and normal-density CD-RW) by realizing a narrower track pitch and a higher linear density, without changing the EFM modulation/demodulation system, the wobble signal frequency and the like employed in the existing normal-density CD-R and normal-density CD-RW. Moreover, the double-density CD-R and CD-RW employ an error correction system called CICR (cross interleave Reed-Solomon code), which is also employed in the existing normal-density CD-R and CD-RW. Thus, a higher recording density is realized while maintaining the compatibility with the normal-density CD-R and CD-RW without largely changing the circuit structure of the optical disc device.
Meanwhile, in the double-density CD-R and CD-RW having the recording density increased by a narrower track pitch and a higher linear density, the size of a defect such as a scratch on a recording mark is relatively larger than in the normal-density CD-R and CD-RW. That is, in the double-density CD-R and CD-RW, the burst error length is greater than in the normal-density CD-R and CD-RW.
Therefore, the double-density CD-R and CD-RW are more vulnerable to burst errors than the normal-density CD-R and CD-RW. If error correction with the CIRC employed in the existing normal-density CD-R and CD-RW is used as it is, there is a high probability that some errors cannot be corrected and that reading of data cannot be carried out appropriately.
In order to perform error correction for burst errors, it is effective to set a large delay parameter of the CIRC so as to elongate the interleave length. However, if the interleave length is set to be too long, many memories must be provided in the optical disc device which carries out error correction processing and there arises a problem of cost. Therefore, in the case of carrying out error correction processing with the CIRC for the double-density CD-R and CD-RW, it is required to set the delay parameter at an appropriate value.
The optical disc device is required not only to be capable of carrying out appropriate recording/reproduction of data to/from the double-density CD-R and CD-RW but also to have so-called compatibility to handle the existing normal-density CD-R and CD-RW.
In view of the foregoing status of the art, it is an object of the present invention to provide a data recording device and a data reproducing device which are capable of carrying out appropriate recording and reproduction of data to and from an optical disc having an increased recording density and which are also capable of handling an optical disc of the existing format, and to provide an optical disc having a high recording density in which appropriate error correction processing is carried out.
A data recording device according to the present invention is adapted for carrying out recording of data onto a first optical disc prescribed by a first standard and for carrying out recording of data onto a second optical disc prescribed by a second standard and having a higher recording density than the first optical disc. The device comprises: data input means to which data to be recorded is inputted; first interleave processing means for performing interleave processing with a first delay parameter on the data inputted to the data input means; second interleave processing means for carrying out interleave processing with a second delay parameter greater than the first delay parameter on the data inputted to the data input means; switching means for carrying out switching between the first interleave processing means and the second interleave processing means; data writing means for writing the data interleaved by the first interleave processing means or the second interleave processing means onto the optical disc; and disc discrimination means for discriminating whether the optical disc on which the data is written by the data writing means is the first optical disc or the second optical disc having a higher recording density than the first optical disc; wherein when it is determined by the disc discrimination means that the optical disc on which the data is written by the data writing means is the first optical disc, the switching means selects the first interleave processing means and the data writing means writes onto the first optical disc the data interleaved with the first delay parameter by the first interleave processing means; and wherein when it is determined by the disc discrimination means that the optical disc on which the data is written by the data writing means is the second optical disc having a higher recording density than the first optical disc, the switching means selects the second interleave processing means and the data writing means writes onto the second optical disc the data interleaved with the second delay parameter by the second interleave processing means.
A data recording device according to the present invention is adapted for carrying out recording of data onto a first optical disc prescribed by a first standard and for carrying out recording of data onto a second optical disc prescribed by a second standard and having a higher recording density than the first optical disc. The device comprises: data input means to which data to be recorded is inputted; interleave processing means for carrying out interleave processing on the data inputted to the data input means while switching a first delay parameter and a second delay parameter greater than the first delay parameter; switching means for controlling switching between the first delay parameter and the second delay parameter; data writing means for writing the data interleaved by the interleave processing means onto the optical disc; and disc discrimination means for discriminating whether the optical disc on which the data is written by the data writing means is the first optical disc or the second optical disc having a higher recording density than the first optical disc; wherein when it is determined by the disc discrimination means that the optical disc on which the data is written by the data writing means is the first optical disc, the switching means selects the first delay parameter and the data writing means writes onto the first optical disc the data interleaved with the first delay parameter; and wherein when it is determined by the disc discrimination means that the optical disc on which the data is written by the data writing means is the second optical disc having a higher recording density than the first optical disc, the switching means selects the second delay parameter and the data writing means writes onto the second optical disc the data interleaved with the second delay parameter.
A data reproducing device according to the present invention is adapted for carrying out reproduction of data interleaved with a first delay parameter from a first optical disc prescribed by a first standard and for carrying out reproduction data interleaved with a second delay parameter greater than the first delay parameter from a second optical disc prescribed by a second standard and having a higher recording density than the first optical disc. The device comprises: data reading means for read out the data from the first optical disc or the second optical disc having a higher recording density than the first optical disc; first deinterleave processing means for performing deinterleave processing on the data interleaved with the first delay parameter, read out from the first optical disc by the data reading means; second deinterleave processing means for performing deinterleave processing on the data interleaved with the second delay parameter, read out from the second optical disc by the data reading means; switching means for carrying out switching between the first deinterleave processing means and the second deinterleave processing means; data output means for outputting the data deinterleaved by the first deinterleave processing means or the second deinterleave processing means; and disc discrimination means for discriminating whether the optical disc from which the data is read out by the data reading means is the first optical disc or the second optical disc; wherein when it is discriminated by the disc discrimination means that the optical disc from which the data is read out by the data reading means is the first optical disc, the switching means selects the first deinterleave processing means and the data output means outputs the data deinterleaved by the first deinterleave processing means; and wherein when it is discriminated by the disc discrimination means that the optical disc from which the data is read out by the data reading means is the second optical disc, the switching means selects the second deinterleave processing means and the data output means outputs the data deinterleaved by the second deinterleave processing means.
A data reproducing device according to the present invention is adapted for carrying out reproduction of data interleaved with a first delay parameter from a first optical disc prescribed by a first standard and for carrying out reproduction data interleaved with a second delay parameter greater than the first delay parameter from a second optical disc prescribed by a second standard and having a higher recording density than the first optical disc. The device comprises: data reading means for read out the data from the first optical disc or the second optical disc having a higher recording density than the first optical disc; deinterleave processing means for carrying out first deinterleave processing in the case where the data read out from the optical disc by the data reading means is the data interleaved with the first delay parameter, and for carrying out second deinterleave processing in the case where the data read out from the optical disc by the data reading means is the data interleaved with the second delay parameter; switching means for controlling switching between the first deinterleave processing and the second deinterleave processing; data output means for outputting the data deinterleaved by the deinterleave processing means; and disc discrimination means for discriminating whether the optical disc from which the data is read out by the data reading means is the first optical disc or the second optical disc; wherein when it is discriminated by the disc discrimination means that the optical disc from which the data is read out by the data reading means is the first optical disc, the switching means selects the first deinterleave processing and the data output means outputs the data deinterleaved by the first deinterleave processing; and wherein when it is discriminated by the disc discrimination means that the optical disc from which the data is read out by the data reading means is the second optical disc, the switching means selects the second deinterleave processing and the data output means outputs the data deinterleaved by the second deinterleave processing.
An optical disc according to the present invention is adapted for having interleaved data recorded thereon. The optical disc has a data recording area in which data is recorded at a recording density that is substantially twice that of an optical disc prescribed by a predetermined standard; wherein data interleaved with a delay parameter 7/4 times that in the case of performing interleave processing on the data recorded on the optical disc prescribed by the predetermined standard is recorded in the data recording area.